The following generally relates to trimmers and, more particularly, relates to a hand-push type trimmer having a cutting height adjustment device.
Trimmers, which are usually used as common garden tools for trimming lawns, can be divided into two types, namely, a hand-held type and a hand-push type. With respect to hand-push type trimmers, such trimmers typically include a working head and a handle mounted on the rear end of the working head. The working head includes a housing, two rear wheels mounted on the rear end of the housing, and a support element. The support element is positioned below the housing and in front of the rear wheels, contacts with the ground to support the whole working head together with the rear wheels, and is mounted on the housing by a shaft. A blade is further rotatably mounted on the shaft via a blade-shaft. A motor provided in the housing drives the blade-shaft to rotate via a transmission device. In this manner, the blade mounted on the blade-shaft can be rotated together with the blade-shaft so as to cut the grass.
To adjust the cutting height of the trimmers, currently known trimmers also include an adjustment device. Specifically, the adjustment device is used to change the distance between the blade and the ground by adjusting the vertical distance between the support element and the blade. When the vertical distance between the blade and the support element is larger, the distance between the blade and the ground is also larger, and therefore the cutting height is larger. Otherwise, when the distance between the blade and the ground is smaller, the cutting height is also smaller.
This existing adjustment device does, however, suffer a disadvantage in that use of the existing adjustment device may not result in the cutting surface of the blade being positioned substantially parallel to the ground. By way of example, when the cutting height is adjusted to a lower level, that is the blade is moved closer to the ground, the height of the front portion of the working head supported by the support element is reduced, while the rear portion of the working head supported on the rear wheel remains in the initial position and is located at a higher position. Therefore, the whole working head is in a state of tilting forwardly, which causes the cutting surface of the blade to be no longer parallel to the ground. In this state, a flat lawn can not be obtained.